How to Make The Most of Your Least Productive Time
finchblogs.com
finchblogs.com
I've found that approach to be quite effective. In the evenings I also include "go to bed" as an acceptable activity. You might not get more done than if you spend the evening watching TV or surfing Facebook but you'll be much more refreshed and productive the next day.
Lastly: Banning all the "time-wasting" sites on my work machine has worked remarkably well for me.
These authors may seem to prescribe general rules since they write in an authoritative style, but we generally know to take them as considerations